The invention refers to analytical instrument engineering and can be used for analyses of natural and process water, biological and geological samples and air.
The known method of sample atomization is evaporation of the sample in a heated electro-thermal atomizer with subsequent dissociation of evaporated compounds in the gas phase at a temperature of 2000-3000xc2x0 C. [1].
The disadvantage of this method is high consumption of power and presence (in case of atomization of samples having a complicated base) matrix and spectral influences.
Other known methods are atomization in a cooled [2] or a hot [3] hollow cathode. Cathode spraying of the wall material by ions of the ballast gas with energy 100-3000 eV in the discharge with cooled hollow cathode in used mainly for analyses of solid specimens and the in layers analyses. In case of a hot hollow cathode the process of conversion of atoms into the gas phase is mainly determined by thermal evaporation.
The disadvantages of the known methods are: if the above mentioned types of discharges are considered from the point of using them for gas discharge atomization of the sample it will be found that both the cooled and the hot hollow cathode cannot be competitive atomizers as the rate of spraying in the cooled hollow cathode is very lowxe2x80x94the period of complete spraying of a sample amounts scores of minutes and hours. As to the hot hollow cathode rate of atomization of a sample is determined exclusively by thermal evaporation (due to the ejection of the field by thermo-emission electrons)xe2x80x94the process which is sufficiently efficient only at temperatures of 2000-2800xc2x0 C. In this case it is preferable to use a usual electro-thermal atomizer operating at atmospheric pressure as the retentivity period of this device is greater than that of the hot hollow cathode and atomization power is comparable [1].
Functionally the closest to the proposed method is the method of atomization by ionic spraying a sample form the surface of the cold flat cathode (the Grimm""s discharge) in the low pressure discharge spraying by comparatively high ionic amperage (to 1A). In this case the sample spraying rate is rather highxe2x80x94the period of spraying is about 0.3-2 sec. According to this method sprayed atoms are transferred by the gas flow or due to diffusion out of the spraying zone into the analytic zone through which analytic resonance radiation passes [4].
The disadvantages of this method are low maximal volumes of a liquid sample not in excess of 1 mcl which results in low concentration limits of detectionxe2x80x94no more than 10 mcg/l. Besides the known method cannot be used with the high selectivity method of correction of non-selective absorption which besides considerable matrix effects an the influence of the atomizer glow on the results of analyses does not make it possible to analyze samples of complicated composition, particularly bio- and geological samples. Comparatively high power consumed in the process of atomization in the Grimm""s discharge (300 W) prevents from development of a mobile analyzer based on the known method for in-situ determination of elements in water and in the air.
An atom- absorption electro-thermal atomizer is known in the shape of a graphite tube with a dosage opening, heated by electric current [2]. In this device atomization is effected by thermodynamically equalized processes of dissociation of compounds evaporated during the heating of the atomizer.
The disadvantage of the known method is high power consumption and presence of matrix and spectral influences (in case of atomization of samples having a complicated base). From technical point of view the closest to the proposed device is the flat gas discharge atomizer (Grimm""s discharge) in which analyzed atoms are transferred by the gas flow or due to diffusion out of the spraying zone into the analytical zone through which the resonance radiation passes [4].
The disadvantages of this method are low maximal volumes of a liquid sample not to exceed 1 mcl which results in low concentration limits of detectionxe2x80x94no more than 10 mcg/l. Besides comparatively high power consumed by the known device (300 W) prevents from using it as a mobile analyzer intended for in-situ determination of elements in water and in the air.
The closest to the proposed analyzer in technical respect is the Seeman""s atom absorption analyzer that contains a source of resonance radiation, a polarizer, optoacoustic modulator, and inclined plate, a phase plate, an atomizer placed in the transverse magnetic field, a polarizing compensator, a monochromator, a photodetector the signal from which is detected in the recording system and is transmitted to the computer [3].
The disadvantage of the known device is high power consumption which restricts the possibilities of the known device. Besides considerable matrix effects not only hamper but often make direct analysis of samples with complicated composition impossible.